The 'Wolf of Wall Street' actor spoke at the State Department's Our Ocean Conference in Washington yesterday (06.17.14), to decry "the Wild West on the high seas" and called for moves to curb "plundering the ocean and its vital resources" as he vowed to make a hefty donation from his self-titled foundation for "meaningful conservation projects" over the next two years.

He said: "[I'm] here as a concerned citizen of this planet who believes this is the most important issue of our time.

"What we need is sustained activism and courageous political leadership. We cannot afford to be bystanders in this pre-apocalyptic scenario."

The 39-year-old actor went on to speak of his sadness in the changes he has seen to Australia's Great Barrier Reef in recent years.

He said: "Since my very first dive in the Great Barrier Reef in Australia 20 years ago to the dive I got to do in the very same location just two years ago, I've witnessed environmental devastation firsthand.

"What once had looked like an endless underwater utopia is now riddled with bleached coral reefs and massive dead zones."